The invention relates to an inhaler for administering medicaments from blister packs, in which the blister cavities are emptied by means of a pressing-out aid.
Inhalers for administering medicaments to patients in a solid form distributed finely in an air flow, so-called powder inhalers, are used nowadays in great numbers and many embodiments in inhalation therapy. They partially replace the previously customary suspension inhalers, in which the aerosol is produced by means of a halogenated hydrocarbon as propellent gas, and whose use is no longer desirable for reasons of environmental protection. Most of the previously known powder inhalers use a device of a technically relatively complex design, with which a patient gives himself inhalable powder portions (doses) by inhalation.
One possibility of predosing medicaments is the packaging of appropriate portions in so-called "blister packs", which are also used, for example, for packaging tablets with the possibility of hygienic individual removal. EP-B-211 595, GB-A-2,129,691 and GB-A-2,142,246 disclose powder inhalers which release the medicament from blister packs in which it is enclosed in a solid, finely distributed form. A disc-shaped blister pack is inserted into the powder inhalers described in EP-B-211,595 and GB-A-2,129,691, the powder portion is released by a plunger when the inhaler is used, and the blister disc is replaced by a new one when it has been completely emptied. GB-A-2,142,246 relates to an inhaler into which a blister pack comprising a single chamber is inserted and is opened for use with a kind of mandrel.
An inhaler which is easy to handle and is inexpensive is described in the subsequently published DE-A-44 00 084. The inhaler comprises a housing which forms an elongate interior, is sealed off relative to the outside, and has a mouthpiece on a narrow side and an air inlet opening on the opposite side, regions with blister cavities being arranged at least on one main surface of the housing. In one embodiment, the housing comprises an open structure into which one or more strips can be introduced, for example by pushing them or inserting them into a structure which can be pivoted open. In all these embodiments of the inhalers, the user has to press the individual cavities of the blister pack open with his fingers, i.e. exert pressure on the outwardly curved dome so that the thin covering foil tears open and the medicament can drop into the interior of the housing. The disadvantage with these inhalers is that the powder in the blister cavities is mechanically loaded and compressed when the latter are pressed open by the finger, and thus can no longer be finely distributed, or can only be insufficiently distributed, in the inhalation flow.
All these powder inhalers have the disadvantage that they are extremely cumbersome, i.e. the device volume is relatively large in relation to the proportioned dose quantity used. Depending on the volume and number of parts per device, carrying a known powder inhaler can be inconvenient for the patient. Moreover, with the different, often complicated functioning principles, there is the risk that the devices may not be handled properly, or possibly cannot be handled at all, in an emergency (e.g. in an acute asthma attack) or in the case of little technical understanding on the part of the patient.